Fluid controlled actuators are known in the art. According to one design, fluid provided to the actuator is controlled using a control valve actuated by two or more pilot valves. The pilot valves control a pressure supply to the control valve, which actuates the control valve to a first or a second position. Such a configuration has received some success, however, the system is complex, bulky, and requires excessive time to react and change the position of the actuator.
FIG. 1 shows a valve control system 100 according to the prior art. The valve control system 100 as shown in FIG. 1 includes an actuator 101, a pressurized fluid conduit 102, a first pilot valve 103, a second pilot valve 104, and a control valve 105. In response to pressurized fluid acting on the actuator 101, either through conduit 106 or through conduit 107, the piston 108 of the actuator 101 moves between a first and a second position. The pressurized fluid may comprise any manner of substantially incompressible fluid, such as pneumatic or hydraulic fluid, for example. Typically, the pressurized fluid used will depend on the particular application.
The pressurized fluid supplied to the actuator 101 is determined based on the position of the control valve 105. The control valve 105 is actuated using the first and second pilot valves 103, 104. In situations where the pilot valves 103, 104 comprise solenoid pilot valves, excitation of solenoid coils (not shown) will actuate the pilot valve, allowing the pressurized fluid to flow to the control valve 105. For example, if the first pilot valve 103 is actuated, the port 112 of the pilot valve 103 is opened to the port 113, thus allowing the pressurized fluid to act on the first side 127 of the control valve 105 through conduit 123. Pressure acting on the first side 127 of the control valve 105 moves the control valve 105 to a first position. In the first position, port 115 of the control valve 105 is opened to the port 116, thus providing an open path from the conduit 111 to the conduit 107. In this position, pressure acts in chamber 125 moving the piston 108 to the left as shown in FIG. 1, while allowing fluid from chamber 126 to exhaust through port 119 of the control valve 105 via conduit 106.
When it is desired to move the piston 108 in the other direction, the first pilot valve 103 is de-actuated and the second pilot valve 104 is actuated, thereby closing the port 112 from the port 113 and opening the port 120 to the port 121 of the second pilot valve 104. The pressurized fluid can then flow from the conduit 110 to the second side 128 of the control valve 105 to move the control valve 105 to a second position. In the second position, port 115 is opened to port 118 of the control valve 105. The pressurized fluid can then flow from the conduit 111 to the conduit 106 to pressurize the chamber 126 of the actuator 101, thereby moving the piston 108 to the right.
Although the design described above can function in limited situations, the valve control system 100 requires an excessive amount of space, power, and components by requiring the use of two pilot valves. Furthermore, there is a delayed response time in switching the actuator 101 because one pilot valve needs to be de-actuated and another pilot valve needs to be actuated prior to any movement of the control valve 105. In addition, each pilot valve has an inherent delay time, and therefore, providing multiple pilot valves compounds the problem. This delay can create problems in situations where the actuator is switched in a repetitive manner or in situations where a fast response time is required.
Therefore there is a need for a fast responding fluid controlled actuator that also minimizes the materials and space required. The present invention solves this and other problems and an advance in the art is achieved.
Aspects
According to an aspect of the invention, a method for operating a control valve adapted to selectively provide a pressurized fluid supply to an actuator, comprises the step of:
actuating the control valve to a first position to open a fluid flow path from a pressurized fluid supply to the actuator, wherein the pressurized fluid supplied to the actuator also biases the control valve towards a second position.
Preferably, the method further comprises the step actuating the control valve to the second position with the pressurized fluid supplied to the actuator.
Preferably, the pressurized fluid biasing the control valve towards the second position is exhausted once the control valve is in the second position.
Preferably, the step of actuating the control valve to the first position comprises applying a force to a first side of the control valve substantially equal to a pressure of the pressurized fluid biasing the control valve towards the second position.
Preferably, the first position of the control valve opens a fluid flow path from the pressurized fluid supply to a first chamber of the actuator and wherein the second position of the control valve opens a fluid flow path from the pressurized fluid supply to a second chamber of the actuator.
According to an aspect of the invention, an actuation system including a fluid operated actuator, comprises:
a control valve movable between a first position and a second position;
a first fluid conduit coupling the control valve to a first chamber of the fluid operated actuator, wherein the first position of the control valve opens a fluid flow path to pressurize the first fluid conduit and the first chamber with fluid from a pressurized fluid supply; and
a second fluid conduit coupled to the first chamber and adapted to divert a portion of the pressurized fluid supplied to the first chamber to bias the control valve towards the second position.
Preferably, the control valve exhausts the pressurized fluid biasing the control valve once the control valve is actuated to the second position.
Preferably, pressurized fluid exhausted from the first chamber of the fluid operated actuator retains the control valve in the second position.
Preferably, the actuation system further comprises a pressure regulator adapted to reduce the pressurized fluid biasing the control valve towards the second position.
Preferably, the actuation system further comprises a biasing member adapted to substantially close the fluid flow path from the pressurized fluid supply to the fluid operated actuator.
According to an aspect of the invention, an actuation system including a fluid operated actuator, comprises:
a control valve movable between a first position and a second position,
a first fluid conduit coupling the control valve to the fluid operated actuator, wherein the first position of the control valve opens a fluid flow path to pressurize the first fluid conduit and a first chamber of the fluid operated actuator with fluid from a pressurized fluid supply; and
a second fluid conduit coupled to the first fluid conduit and adapted to divert pressurized fluid in the first fluid conduit to bias the control valve towards the second position.
Preferably, the control valve exhausts the pressurized fluid biasing the control valve once the control valve is actuated to the second position.
Preferably, pressurized fluid exhausted from the first chamber of the fluid operated actuator retains the control valve in the second position.
Preferably, the actuation system further comprises a pressure regulator adapted to reduce the pressurized fluid biasing the control valve towards the second position.
Preferably, the actuation system further comprises a biasing member adapted to substantially close the fluid flow path from the pressurized fluid supply to the fluid operated actuator.